On 6/29/11 1:42 AM, "Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote:
>roprabhu, Tom,
>
>Thanks very much for the testing. So on the first glance
>one seems to see a significant performance gain in V0 here,
>and a slightly less significant in V2, with V1
>being worse than base. But I'm afraid that's not the
>whole story, and we'll need to work some more to
>know what really goes on, please see below.
>
>
>Some comments on the results: I found out that V0 because of mistake
>on my part was actually almost identical to base.
>I pushed out virtio-net-limit-xmit-polling/v1a instead that
>actually does what I intended to check. However,
>the fact we get such a huge distribution in the results by Tom
>most likely means that the noise factor is very large.
>
>
>From my experience one way to get stable results is to
>divide the throughput by the host CPU utilization
>(measured by something like mpstat).
>Sometimes throughput doesn't increase (e.g. guest-host)
>by CPU utilization does decrease. So it's interesting.
>
>
>Another issue is that we are trying to improve the latency
>of a busy queue here. However STREAM/MAERTS tests ignore the latency
>(more or less) while TCP_RR by default runs a single packet per queue.
>Without arguing about whether these are practically interesting
>workloads, these results are thus unlikely to be significantly affected
>by the optimization in question.
>
>What we are interested in, thus, is either TCP_RR with a -b flag
>(configure with --enable-burst) or multiple concurrent
>TCP_RRs.
ok sounds good. I am testing your v1a patch. Will try to get some results out end of this week. Thanks.
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